The present invention relates to a three-dimensional shape data processor for processing data concerning a three-dimensional shape to be formed on a flat plate. The present invention also relates to an engraved plate engraved by moving a cutting blade vertically while moving a flat plate in the directions X and Y on the basis of superimposed three-dimensional shape data. In addition, the present invention relates to an engraving apparatus for engraving a flat plate of a noble metal on the basis of three-dimensional shape data.
A three-dimensional shape measuring apparatus measures a three-dimensional shape having a height by using lasers and CCDs (Charge-Coupled Devices). The three-dimensional shape measuring apparatus is widely used for the purpose of making use of three-dimensional shapes in morphological researches based on the measurement of the human body and the regions of the human body and also in the field of medical treatment. As is well known, three-dimensional shape measuring apparatus are generally designed to measure the height at each point in a two-dimensional XY-plane on the principle of trigonometry. Various three-dimensional shape measuring apparatus have heretofore been proposed [for example, see Japanese Patent Application Unexamined Publication (KOKAI) Nos. 58-18110 and 60-220805]. In measurement of the hair of the human body with these conventional apparatus, a missing portion where no measurement data is obtained occurs. Therefore, the measurement accuracy is extremely low. For this reason, it has heretofore been difficult to obtain an engraved medal of good quality using three-dimensional shape measurement data concerning the head. In recent years, however, medals engraved with the pictures of the heads using three-dimensional shape measurement data have been improving in quality as the result of improvements in the measurement accuracy of three-dimensional shape measuring apparatus and improvements in interpolation and correction processing algorithms for measurement data, and automatic medal-engraving apparatus have already been proposed [for example, see Japanese Patent Application Unexamined Publication (KOKAI) No. 2-303900].
FIG. 1 is a diagram for describing a conventional automatic engraving apparatus using three-dimensional shape measurement data, and FIG. 2 is a diagram showing a configuration example of a memory space for three-dimensional shape measurement data. In the figures: reference numeral 31 denotes a three-dimensional shape measuring device; 32 denotes a shape data processor; 33 denotes a three-dimensional cutting machine; 34 denotes a holding means; 35 denotes a dust collector; 36 denotes a tool changing means; 37 denotes a medal selection and supply means; and 38 denotes a medal.
In FIG. 1, the three-dimensional shape measuring device 31 is a means for three-dimensionally measuring a person""s face in profile, for example. The shape data processor 32 is a computer that performs control, arithmetic processing and storage of data measured by the three-dimensional shape measuring device 31 to calculate the width, length and thickness of the person""s face in profile. The three-dimensional cutting machine 33 moves a cutting tool vertically in the direction Z while moving (scanning) the medal 38 in the directions X and Y, which is an object to be engraved, on the basis of the shape data under the control of the shape data processor 32, thereby engraving one side of the medal 38 with a profile of the person. The three-dimensional cutting machine 33 is equipped with the holding means 34, the dust collector 35, the tool changing means 36 and the medal selection and supply means 37 as accessories. The holding means 34 is a vise or the like for holding firmly the medal 38. The tool changing means 36 changes cutting tools, e.g. a drill, a cutter, and an end mill, from one to another in conformity to a portion of each individual medal that is to be cut. The dust collector 35 collects cuttings in one place. The medal selection and supply means 37 has several different kinds of medals, which vary in color, size, etc., prepared in advance according to need, and transfers a medal as selected at one""s desire to the cutting position.
The three-dimensional shape measuring device 31 may be one of those which use various techniques: e.g. a method wherein the height Z at each point in a two-dimensional XY-plane is measured by using two industrial television cameras and CCDs; an optical cutting method wherein a three-dimensional shape is measured by projecting an optical membrane that can be formed by a combinational system comprising a ray scanning or parallel beam magnifying lens system (beam expander) and a cylindrical lens; a moire topography method wherein a grating having slits formed at a uniform pitch is placed at a predetermined distance, and light is projected through the grating to measure a three-dimensional shape; and a method that utilizes a distorted mesh image obtained by projecting a shadow of a mesh-shaped orthogonal grating onto an object.
Three-dimensional shape data measured with such a three-dimensional shape measuring device 31 can be set in a memory space using 8 plane memories of nxc3x97m in the case of 8-bit representation of the height in an nxc3x97m two-dimensional plane as shown in FIG. 2 by way of example. Height information in the three-dimensional shape data is stored in such a manner as to skewer the plane memories at each point. Accordingly, height data at a point P (i,j), for example, is taken out in the form of xe2x80x9c10011010xe2x80x9d by successively reading data from the plane memories at that point. The three-dimensional cutting machine determines and controls the height of the cutting tool, that is, the cutting height, on the basis of the height data. P (i,j) is the cutting position of the medal at this time.
FIG. 3 is a diagram for describing problems arising in the case of synthesis processing of three-dimensional shape data.
The following is a description of a case where a profile is engraved on a medal or the like by the above-described conventional automatic engraving apparatus using three-dimensional shape data measured by the three-dimensional shape measuring device. In such a case, first, two 3-dimensional shape data are measured by the three-dimensional shape measuring device. As shown in part (A) of FIG. 3, one of the two data is underlay engraving data, and the other is overlay engraving data, which is to be overlaid on the underlay engraving data. The two data are input to an engraving data synthesis processing unit 41, in which after each data has been positioned, synthesis processing is carried out. In the synthesis processing by the engraving data synthesis processing unit 41, the underlay engraving data is first written into the memory, and the overlay engraving data is written over the underlay engraving data to perform updating. Consequently, portions of the underlay engraving data that are overlaid with the overlay engraving data are rewritten and thus concealed. In other words, those portions of the underlay engraving data are erased, and a synthesis result 42 is obtained.
However, when synthesis processing is carried out as stated above, the synthesis result 42 shown in part (A) of FIG. 3 has a Y-Yxe2x80x2 section such as that shown in part (B) of FIG. 3, by way of example. That is, the underlay engraving data {circle around (1)} is zero (reference height) at the boundary contour X of the overlay engraving data. Thus, the data becomes discontinuous. When engraving a medal, the three-dimensional cutting machine moves a cutting tool vertically in the direction Z according to the height data while moving the medal in the directions X and Y as stated above. Therefore, when the data is discontinuous as shown in part (B) of FIG. 3, it is impossible to perform cutting while moving the medal at constant speed, and during the cutting process, the movement must be temporarily stopped at the boundary contour X, which forms a step. Accordingly, the cutting efficiency lowers markedly. In addition, because a step is formed on the engraved surface, smooth finish cannot be expected.
To connect the underlay engraving data and the overlay engraving data smoothly at the boundary, if, as shown in part (C) of FIG. 3, either of the underlay engraving data and the overlay engraving data that is higher than the other is employed and the two data are switched from one to the other at the portions of the same height, that is, if the portions of the same height are defined as a boundary, it is impossible to obtain the contour of the underlay engraving data nor the contour X of the overlay engraving data. In such a case, in particular, the contour X of the overlay engraving data is unfavorably deformed in the synthesis result 42 shown in part (A) of FIG. 3.
The present invention was made to solve the above-described problems, and an object of the present invention is to enable three-dimensional shape data to be combined together into favorable engraving data and to allow engraving to be performed efficiently on the basis of three-dimensional shape data.
To attain the above-described object, the present invention provides a three-dimensional shape data processor for processing data concerning a three-dimensional shape to be formed on a flat plate. The three-dimensional shape data processor is characterized by having a synthesis processing means for performing synthesis processing such that three-dimensional shape data are partially superimposed on one another, and at an overlap portion, either one of the three-dimensional shape data is left as it is, while the other is erased. The three-dimensional shape data processor further has an interpolation processing means for performing interpolation processing by providing a predetermined interpolation region at a boundary between the three-dimensional shape data subjected to the synthesis processing. The interpolation processing means performs interpolation so that the height changes continuously between the three-dimensional shape data combined together through the interpolation region.
In addition, the present invention provides an engraved plate engraved by moving a cutting blade vertically while moving a flat plate in the directions X and Y on the basis of superimposed three-dimensional shape data. The engraved plate is characterized in that three-dimensional shape data are partially superimposed on one another, and at an overlap portion, either one of the three-dimensional shape data is left as it is, while the other is erased. Moreover, a predetermined interpolation region is provided at a boundary portion between the three-dimensional shape data, and interpolation is performed so that the height of the three-dimensional shape data changes continuously through the interpolation region.
In addition, the present invention provides an engraving apparatus for engraving a flat plate of a noble metal on the basis of three-dimensional shape data. The engraving apparatus is characterized by having a storage means for storing three-dimensional shape data, a holding means for holding the flat plate in a cutting fluid, a cutting means having a cutting blade to perform cutting on the flat plate, and a drive control means for moving the holding means in the directions X and Y and, at the same time, moving the cutting means vertically in the direction Z on the basis of the three-dimensional shape data stored in the storage means. The flat plate is engraved by moving the cutting means vertically in the direction Z while moving the flat plate held in the cutting fluid in the directions X and Y.